Every day is a new adventure for me, sincefrom when I wake up until I fall sleep.

Note: “every day” is correct here. Written as one word, it is an adjective (eg: my everyday clothes, an everyday occurrence, etc.) Written as two words, it’s a noun, which is what you want 🙂

Many times I think my life is wonderful still, I have two amazing childrens.

“Still” implies life is good despite something bad that has happened. (Eg my life is still good even though I’m in debt). “Children” is the plural of “child”, so no “s” is needed.

Sebastian is a great boy, a. Although hie has disabilities, he is improving every day.

Previous was a run on sentence with comma splice.

sSome times I think that Sebastian can’t do a lot of things, but he looks like inexhaustible.

Using “but” indicates you’re contrasting two things. I’m not 100% clear your intention here. My edit would mean that you think he can’t do a lot things (because of your knowledge of his abilities, etc.), but when you look at him he looks like he would, in fact, be able to do everything.

“Looks like” would be paired with a noun (eg “he looks like a turtle”). “Looks” is paired with adjectives.

I wish withhave great hope that Sebastian become ins a great person.

Every smile she gives me is the mosta treasure that I save in my memory.

You could use “the most treasured” as an adjective (eg “the necklace from my mom is the most treasured item she ever gave me”).
Since you’re saving something in your memory, you want a noun (ie: “treasure”)

Every day is a new adventure for me, since I wake up untilfrom the moment I wake up to the moment I fall asleep.

Many timesOften, I think my life is wonderful still,. I have two amazing childrens.

Sebastian is a great boy, alt. Though hie has disabilities, he is improving every day.

These two clauses should be separated.

some times I thinkIn spite of the fact that Sebastian does a lot of things, but he looks likehe still looks inexhaustible.

I wish with great hope that Sebastian become ins a great person.

EvHery smile she give me iss are the most tpreasure that I savecious things in my memory.

I hope that Marianita fulfills all your wishes.

This isn't grammatically incorrect but I'm not sure what you're saying here. Are you referring to the wishes of society, of family?